1. Field of the Invention
The present invention relates to a reaction solution, a set of the reaction solution and an ink, an inkjet recording apparatus and an image recording method, and particularly relates to a reaction solution to be used with an ink when printing is performed on a recording medium, a set of a reaction solution and an ink, and an image recording method using the same.
2. Related Background Art
Various propositions have been made for the inkjet recording method that uses a liquid other than the ink jet ink for improving image quality, where the liquid is applied to a recording medium before the recording ink is ejected to form an image. There are, for example, a method in which a liquid containing a basic polymer is applied, and then an ink containing an anionic dye is applied (Japanese Patent Application Laid-Open No. S63-60783A), a method in which a liquid containing a chemical species and a liquid containing a compound reactive with the reactive species are mixed on the recording medium (Japanese Patent Application Laid-Open No. S63-22681A), and a method in which a liquid containing an organic compound having two or more cationic groups per molecule is applied, and then an ink containing an anionic dye is applied (Japanese Patent Application Laid-Open No. S63-299971A). Furthermore, there are a method in which an acid liquid containing succinic acid or the like is applied, and then an ink containing an anionic dye is applied (Japanese Patent Application Laid-Open No. S64-09279A), and a method in which a liquid insolubilizing a dye is applied before an ink is applied (Japanese Patent Application Laid-Open Nos. S64-63185A and S64-69381A).
These methods described above are to inhibit feathering of the image, and to improve durability of the image by the precipitation of the dye applied on a recording medium. These methods, however, are not so effective in preventing bleeding between color inks of different colors, since the distribution of the dye precipitated on the recording medium tends to be uneven, which may cause unevenness in the image. Particularly, if normal paper is used as a recording medium, pulp fibers do not receive sufficient application, and this tendency of unevenness sometimes becomes more conspicuous.
On the other hand, there has been proposed, for pigment ink systems, an ink set comprised of an ink containing a pigment dispersion and an ink containing a polyvalent metal in order to alleviate bleeding in a multicolor print (Japanese Patent Application Laid-Open No. H09-118850A). This method, however, has the constraint that the polyvalent metal to be contained in the ink should be compatible with the coloring material in view of ink stability, as well as a problem of insufficient image density.
In order to solve the above-described problems such as uniform image and high image density, various methods have been proposed in which a liquid composition containing a polyvalent metal ion is first applied onto a recording medium, and then printing is carried out with an ink reactive with the liquid composition (Japanese Patent Application Laid-Open Nos. S63-299970A, H06-86142A, H09-207424A, H11-349873A, 2000-94825A and the like).
However, there are still problems that it is difficult to obtain optical density as high as required by recent demand for high image quality, or that image quality may differ from the initial stage to the later stages.